Thermal packs are used for various purposes. Cold thermal packs are used to help control edema (swelling) in human and animal tissue. Cold thermal packs are also used to help control body temperature (cooling vests, cooling collars, hats, etc.). Warming thermal packs are used for medicinal purposes as well as personal comfort. A continuing problem with thermal packs (cold or warm) is the irregular distribution of thermal effect because of irregular contact or external influence.
FIG. 1 shows a prior art thermal pack 5. The thermal pack 5 has two layers or sheets 1, 2, which are joined along a peripheral edge 4 to form a compartment or “bubble” 3 containing thermal material (e.g. ice; chemical mixtures; gels). Commercially available thermal packs are typically manufactured by forming a seal around the periphery of the two layers or sheets 1, 2. This process forms a pack 5 that has a seam or lip 4 that usually extends peripherally and horizontally in the same plane as the seam formed at the junction of the two layers 1, 2, and which runs along the periphery of the pack 5. Because of the thermal process used to seal the pack layers, this peripheral lip 4 often becomes hard, and depending upon the type of material, can feel sharp against the skin. FIG. 2 is a cross-section view illustrating how the peripheral edge 4 of a prior art thermal pack 5 can cause irritation when it comes into contact with the skin of a user. As shown in FIG. 2, when the prior art thermal pack 5 containing thermal material 8 is pressed against the skin 100 of a user, the natural curvature of the skin forces the skin 100 to contact the peripheral edge 4 of the pack 5, causing the skin to be depressed and/or rubbed, and causing irritation at the point of contact 6. Such irritation may cause the wearer to abandon use before the benefits of the thermal pack can be fully experienced.